The 15 ml amber dropper (Euro) bottle is a little shorter so
the glass dip tube angles to the side of the bottle to
just fit, but not well. The 1/2 oz (15 ml capacity) Boston
round bottle is a better choice

These can also be used on the 30 ml dropper (Euro)
bottles (glass pipette comes to about 3/4" of the bottom)
but the 1 oz Boston rounds with their size of glass dropper
caps are a better choice

These would also fit on the larger sizes of dropper
(Euro) bottles but the glass pipette would be short.
The Boston round line is a better choice if looking for a
glass dropper bottle combination

They do not fit the 5 ml or 10 ml,
those bottles are too short

Combine these glass dropper caps with the 1/2 oz Boston
round bottles to make the popular 15 ml glass dropper
bottle